BEIRUT — Gunmen snatched 47 Iranian pilgrims just outside Damascus on Saturday in a brazen attack that revealed the growing instability at the center of President Bashar Assad's power.

The abduction came as Syrian troops moved to crush one of the last rebel-dominated neighborhoods in the capital, shelling the area heavily. No group immediately claimed responsibility, although Iranian state media blamed the rebels fighting the Assad regime.

The pilgrims were on a bus taking them from the suburb of Sayeda Zeinab, about 10 miles (16 kilometers) south of Damascus, to the airport to return home when they were kidnapped, according to the Iranian state news agency, IRNA.

Mainly Shiite Iran is a close ally of the beleaguered Syrian government, which is dominated by the Alawite sect, an offshoot of Shiism. Syria has long welcomed Iranian pilgrims visiting the ornate gold-domed shrine of Sayeda Zeinab, the Prophet Muhammad's granddaughter; up to 700,000 pilgrims used to come every year, IRNA said, although the number has fallen precipitously since the 17-month uprising that has killed an estimated 19,000.

Late Saturday, Iran's semiofficial Fars news agency announced that Syrian forces had freed the hostages, but cited no source. There was no confirmation from the Syrians.

Still, the kidnapping underscores the inability of the regime, which is fighting rebels in all the major cities of the country, to even control the immediate environs of the capital city.

Just a few miles from the site of the kidnapping, regime forces encircled the southern Damascus neighborhood of Tadamon, a bastion of rebel support. Heavy explosions shook the capital Saturday, and plumes of smoke rose from the neighborhood that was attacked by regime forces the night before.

"We heard heavy bombing since dawn," a witness in Damascus told The Associated Press, asking that his name not be used out of fear for his personal safety. "Helicopters are in the sky." By nightfall the state media reported the whole capital to be in government hands, but such announcements have in the past proved premature.

The kidnapping was the largest such abduction of Iranian pilgrims, although it was not the first.

In January, gunman kidnapped 11 Iranian pilgrims driving from the Turkish border to Damascus. At least two were later freed with Turkish mediation. Seven Iranian engineers building a power plant in central Syria were kidnapped in December and the Free Syrian Army claimed responsibility, accusing them of aiding Assad's regime. At least four have been released.

Sunni Muslim militants often attacked Iranian pilgrims visiting holy sites in neighboring Iraq during the years of unrest there. There have been reports of an influx of such militants into Syria since the uprising began. Targeting the pilgrims maybe seen as attacking allies of the regime.

A Syrian-based Sunni militant group posted on jihadi web forums that it had kidnapped and executed a prominent Syrian television broadcaster, who had been reported missing since July 19.

The al-Nusra Front announced that Mohammed Saeed, presenter for the Syrian "Talk of the Town" program, had been captured and put on trial before being executed.

"Perhaps this operation and others will serve as an example to all who support this tyrannical regime," said the statement, which included a photo of Saeed, apparently while in the militants' custody.

The new violence in Damascus reflected the regime's difficulty in keeping rebels down even at the center of its rule. Two weeks ago, the government crushed the rebels' biggest yet campaign in the capital city that included incursions by fighters into downtown neighborhoods and an audacious bomb attack that killed four members of Assad's inner circle.

The main battle, however, has now moved to Syria's largest city of Aleppo, some 350 kilometers (215 miles) north of Damascus where rebels seized several neighborhoods two weeks ago and have proved difficult to dislodge.

On Saturday, hundreds of rebels attacked the strategic television broadcast building and were only driven off after a three-hour battle in which the government resorted to jet fighters and helicopter gunships.

Clashes were also reported around the medieval citadel, a symbol of the city that dominates its ancient center, suggesting the rebels are trying to expand their hold.

Aleppo is Syria's commercial hub and it's close to the Turkish border where the rebels have their rear bases. If the opposition were to gain control, it would be a major blow to the regime and a possible opposition base of operations.

More heavily armed government troops, however, have been steadily shelling the rebel-controlled parts of the city, particularly Salaheddine neighborhood, suggesting Aleppo will not fall to the rebels anytime soon.

On Saturday, China said the West should be blamed for obstructing diplomatic and political efforts to restore order and peace in Syria. Wang Kejian, a deputy director of north African and west Asian affairs at the Chinese Foreign Ministry, told a news conference that Western countries had hindered and sabotaged the political process by advocating regime change.

Wang reiterated China's stance that the solution to the Syria crisis should be a political one and that it is opposed to any military intervention.

Turkey also reported the defection of another Syrian general, along with five colonels who came over the border with a group of refugees. The general would be the 29th to defect since the start of the uprising. Despite the defections, however, the Syrian army has largely remained intact.